110 likes | 246 Vues
This document outlines the concept of site-based bio-surveillance utilizing differential detection to monitor geographically constrained populations for signs of disease outbreaks. It emphasizes the advantages of centralized data collection and permissions, as well as the need for stable populations at specific sites like military bases and university campuses. The differential detection approach involves tracking call patterns and employing statistical models to identify significant deviations, aiding in early outbreak detection while ensuring privacy through anonymization.
E N D
Site Surveillance Using Differential Detection Murray Campbell
Acknowledgements • Based on work of Vijay Iyengar, Ed Pednault • This material is based upon work supported by the Air Force Research Laboratory(AFRL)/Defense Advanced Research Projects Agency (DARPA) under AFRL Contract No. F30602-01-C-0184. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the AFRL and/or DARPA. Approved for Public Release, Distribution Unlimited (5/3/2004). Site Surveillance Using Differential Detection
Site-Based Bio-Surveillance The monitoring of a geographically constrained site with a relatively stable population for signs of disease outbreak. • Example of sites could include work sites, university campuses, or military bases • The population need not be present 24 hours a day Site Surveillance Using Differential Detection
What makes “Site-Based” Bio-Surveillance Different? • Increased data availability • Central authority for permissions • Centralized data collection • “Permissive” • “Sensitive” data more likely to be available • Relatively stable population • May be more homogenous than general population • Geographically constrained • Spatial considerations are greatly reduced or eliminated Site Surveillance Using Differential Detection
Differential Detection Approach • Define sites (regions) that normally track each other • Determine appropriate model for measured quantities • Quantify normal variation in the tracking • Detect significant deviations in the tracking • Signifies event affecting one of the sites Site Surveillance Using Differential Detection
Differential Detection Approach Reference Site Reference Site Target Site Reference Site Reference Site Reference Site Site Surveillance Using Differential Detection
Experiments • Monitor phone calling patterns at two IBM sites • Yorktown, Hawthorne (10 miles apart) • Counts of calls/callers to medical facilities • Counts of all calls/callers • Currently being collected on a daily basis • Privacy ensured through • Anonymization of calling number • No reporting of called number Site Surveillance Using Differential Detection
Method • Assume underlying Poisson process • Define two time windows • History, Test • Model ratio of counts in a window • Use Chi-squared statistic to detect deviations • Empirical variance estimate Site Surveillance Using Differential Detection
Medically-Related Calls Site Surveillance Using Differential Detection
All Calls Site Surveillance Using Differential Detection
Issues • Requires • Good tracking • Significant volumes • Can use • Raw counts • Counts adjusted by domain knowledge • If sites respond differently to some phenomenon Site Surveillance Using Differential Detection